Locking issue

Below is the occurrence of the issue..

Stats gather started non partition table -TAB1 as part of auto gather job (i.e. gather_database_stats_job_proc) and it started around 10:08PM. And multiple internal sqls were running as part of that stats gather and around 11:06PM we last saw the below statement executed in that session.

select /*+ opt_param('_optimizer_use_auto_indexes' 'on') no_parallel_index(t, "XXX") dbms_stats cursor_sharing_exact use_weak_name_resl dynamic_sampling(0) no_monitoring xmlindex_sel_idx_tbl opt_param('optimizer_inmemory_aware' 'false') no_substrb_pad no_expand index_ffs(t,"XXXX") */ count(*) as nrw,count(distinct sys_op_lbid(228647,'L',t.rowid)) as nlb,count(distinct hextoraw(sys_op_descend("XXX")||sys_op_descend("XXX")||sys_op_descend("XXX"))) as ndk,sys_op_countchg(substrb(t.rowid,1,15),1) as clf from "USER1"."TAB1" sample block ( .0413656293,1) t where "XXX" is not null or "XXX" is not null or "XXXX" is not null

Then at around 11:07:00.687 PM, we have below application query started running from multiple sessions and started experiencing "row cache lock" with P1(cache id=62) as "dc_realtime_colst" , P2(mode) as 3 i.e. 'share mode' and P3(request) as 3 i.e. 'share mode'. Nothing found in the blocking session. Subsequently few other session of same query went into "row cache lock" with P1(cache id=63) as "dc_realtime_tabst" , P2(mode) as 0 i.e. 'null mode - not locked' and P3(request) as 3 i.e. 'share mode'.

 Then we noticed at around 11:07:00.695 PM , the same stats gather session itself started experiencing "row cache lock" with P1(cache id=62) as "dc_realtime_colst" , P2(mode) as 0 i.e. 'null mode - not locked' and P3(request) as 5 i.e. 'exclusive mode'.

SELECT /*+ FULL(P) +*/ * FROM "TAB1" P

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |

| 0 | SELECT
STATEMENT | | | | 3777K(100)| | | 1 | TABLE ACCESS STORAGE FULL FIRST ROWS| TAB1 | 733M| 169G| 3777K (1)| 00:02:28 |

Outline Data

 /*+

   BEGIN_OUTLINE_DATA    IGNORE_OPTIM_EMBEDDED_HINTS    OPTIMIZER_FEATURES_ENABLE('19.1.0')    DB_VERSION('19.1.0')    OPT_PARAM('_fix_control' '27268249:0')

   FIRST_ROWS    OUTLINE_LEAF(_at_"SEL$1")

   FULL(_at_"SEL$1" "P"_at_"SEL$1")